A transmission-type photonic nanojet generator based on suspended core optical fiber

Abstract

The invention discloses a transmission-type photon nanojet generator based on a suspended core optical fiber, comprising a light source, a single-mode optical fiber, a suspended core optical fiber, a high-resolution CCD, and a three-dimensional high-precision displacement stage; the light emitted by the light source is output through the single-mode optical fiber and vertically incident from the side of the suspended core optical fiber attached to the core, and a transmission-type photon nanojet is generated on the shadow surface of the core of the suspended core optical fiber, and the photon nanojet is observed by a high-resolution CCD; the three-dimensional high-precision displacement stage controls the single-mode optical fiber so that the light output by the core of the single-mode optical fiber can directly irradiate the core of the suspended core optical fiber through the cladding of the suspended core optical fiber; there is a large air hole inside the cladding of the suspended core optical fiber, the core is suspended on the inner wall of the air hole, and the single-mode optical fiber is placed vertically with the suspended core optical fiber. The core of the suspended core optical fiber of the present invention is exposed in the air hole, and the outer side is protected by the cladding, so that the core surface is not damaged, not easy to be contaminated, and has higher stability.

Description

Technical Field

[0001] The invention belongs to the field of optical technology, and in particular relates to a transmission-type photon nano-jet generator based on a suspended core optical fiber. Background Art

[0002] Photonic nanojets are localized beams with narrow lateral dimensions, high intensity, and long propagation distance. Among the many advantages of photonic nanojets, their high energy focusing feature is the most widely used. Higher energy and smaller volume are the most direct advantages of photonic nanojets. Highly focused electromagnetic field energy can cause nonlinear effects in materials. The application of photonic nanojets can be expanded to the field of enhancing the interaction between light and matter. For example, the photonic nanojets generated by traditional microspheres are in close contact with the sample surface, which will generate an enhanced focusing field on the sample surface and certain areas at the bottom of the photonic nanojets generator, making the interaction between light and objects show new characteristics - super-resolution imaging. At the same time, other characteristics of photonic nanojets also have broad application prospects. For example, gradient field distribution and microlens effect can promote the generation of new photonic nanojets, as well as biophotonic waveguides. In summary, due to the characteristics of high intensity and extremely narrow lateral size, photon nanojets have potential application prospects in optical detection, optical manipulation of nano-sized objects, maskless subwavelength and lithography, low-loss coupled resonant optical waveguides, and ultra-high-density optical data storage. Many existing studies have shown that photon nanojets generated by spheres can reach sub-diffraction limits, and through the design of materials, the lateral width of photon nanojets can reach λ / 2, which provides new possibilities for the research field of photon nanojets.

[0003] Nanolithography manufacturing based on beyond the diffraction limit and high-density optical data storage are both examples of applications that are expanded by utilizing the sub-diffraction limit and near-field effect of photon nanojets generated by traditional microspheres. However, due to the small structure of microspheres, it is more difficult to operate experimentally, and it is very easy to be contaminated by the external environment, resulting in unsatisfactory photon nanojets. The present invention uses the core of the suspended core optical fiber as a device for generating photon nanojets. The overall size of the optical fiber is moderate and easy to operate. In addition, the core is attached to the air hole, and the generated photon nanojets are also located in the air hole, which is conducive to the observation and application of photon nanojets. Summary of the invention

[0004] The object of the present invention is to provide a transmission-type photon nanojet generator based on a suspended core optical fiber.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A transmission-type photon nanojet generator based on a suspended core fiber comprises a light source, a single-mode fiber, a suspended core fiber, a high-resolution CCD and a three-dimensional high-precision displacement stage; a large air hole is provided inside the cladding of the suspended core fiber, and the fiber core is suspended on the inner wall of the air hole; the single-mode fiber is placed vertically to the suspended core fiber; the three-dimensional high-precision displacement stage controls the single-mode fiber so that the light output from the core of the single-mode fiber can directly irradiate the core of the suspended core fiber through the cladding of the suspended core fiber; the light emitted by the light source is vertically incident from the side of the suspended core fiber attached to the core after being output by the single-mode fiber, generating a transmission-type photon nanojet on the shadow surface of the fiber core, and the photon nanojet is observed by a high-resolution CCD.

[0007] Furthermore, the diameter of the suspended core optical fiber is 125 microns, the diameter of the air hole is 70-90 microns, and the core diameter is 3-12 microns; the diameter of the single-mode optical fiber is 125 microns, and the core diameter is 8-10 microns.

[0008] Furthermore, the cladding of the suspended core optical fiber is processed with a microgroove on one side of the air hole, and the core is exposed to the outside, so that the photon nanojet generated by the suspended core optical fiber can be observed by a high-resolution CCD.

[0009] Furthermore, the photon nanojet generated by the core of the suspended core optical fiber is located in the air hole.

[0010] Furthermore, the suspended core optical fiber is a quartz optical fiber with a small difference in refractive index between the core and the cladding, or a microstructure optical fiber made of glass or semiconductor material with a large difference in refractive index between the core and the cladding.

[0011] Furthermore, the output end face of the single-mode optical fiber is cut vertically and the end face is flat, so that the light beam is evenly irradiated onto the suspended core optical fiber.

[0012] Furthermore, the modulation of the photon nanojet is achieved by thinning the core of the suspended core optical fiber, filling the air hole with media of different refractive indices, and changing parameters including the light source.

[0013] Furthermore, the wavelength range of the monochromatic light source is 400-1600nm.

[0014] The beneficial effects of the present invention are:

[0015] 1. The present invention generates a transmission-type photon nanojet through the core of a suspended core optical fiber. The core size is small, but there is a large cladding outside the core, so the entire optical fiber size is moderate, compared with microparticles of a few microns, making the device convenient and fast in experimental operation and can be more conveniently integrated into the optical path.

[0016] 2. The core of the suspended core optical fiber of the present invention is exposed in the air hole and is protected by a cladding layer on the outside, so that the core surface is not damaged and is not easily contaminated. Compared with a single microparticle, the present invention has higher stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of a transmission-type photon nanojet generator system based on a suspended core optical fiber according to the present invention;

[0018] FIG2( a ) is a schematic cross-sectional view of a suspended core optical fiber of the present invention;

[0019] FIG2( b ) is a schematic diagram of the suspended core optical fiber of the present invention after polishing;

[0020] Figure 3 It is an enlarged schematic diagram of the installation position of the single-mode optical fiber and the suspension core optical fiber of the present invention;

[0021] Figure 4 Schematic diagram of the photon nanojet generated by the suspended core optical fiber according to the numerical simulation of the present invention;

[0022] Figure 5 This is a diagram of the photon nanojet phenomenon observed in the experiment of the present invention;

[0023] FIG6( a ) is the lateral dimension data of the photon nanojet of the present invention;

[0024] FIG. 6( b ) is the longitudinal dimension data of the photon nanojet of the present invention. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings.

[0026] Combination Figure 1 Figure 2 Figure 3 , Figure 5 As shown in FIG. 6 , the transmission-type photon nanojet generator based on the suspended core fiber of the present invention includes a monochromatic light source, a single-mode fiber 1, a suspended core fiber 2, a high-resolution CCD 3 and a computer. As shown in FIG. 2 (b), the suspended core fiber 2 is first side-casted using the wheel-type side-casting technology, so that the photon nanojet generated by the suspended core fiber 2 can be observed. There is a relatively large air hole 4 on the inner side of the cladding 5 of the suspended core fiber 2, and the diameter of the air hole 4 is 88 microns. The core 6 is attached to the inner wall of the air hole 4, and its diameter is 12 microns; the core diameter of the single-mode fiber 1 is 9 microns. The position of the core 6 of the suspended core fiber 2 is observed and adjusted under a microscope, and the single-mode fiber 1 is perpendicular to the suspended core fiber 2, and the side of the air hole 4 where the core 6 is attached is close to the output end of the single-mode fiber 1. The output end of the single-mode fiber 1 is fixed on a three-dimensional precision displacement stage, and the displacement stage is adjusted so that the light output by the single-mode fiber 1 can be irradiated on the core 6 of the suspended core fiber 2.

[0027] After the light in the single-mode optical fiber 1 is output, it first passes through the cladding 5 of the suspension core optical fiber 2, and then irradiates the core 6 of the suspension core optical fiber 2. The light beam irradiates the core 6 from the side. After the light beam passes through the core 6, a transmission-type photon nanojet effect is generated on the shadow surface of the core 6. Finally, a high-resolution CCD 3 is used to observe the generated photon nanojet, and an image of the photon nanojet at the maximum intensity value is obtained as shown in FIG. Figure 5 As shown. Since the generating device is the core 6 of the suspended core optical fiber 2, the generated photon nanojet is an axisymmetric ellipse that is narrow on both sides and wide in the middle. The data is extracted along the vertical direction at the center to obtain its lateral size as shown in Figure 6(a). The three-dimensional precision translation stage is controlled to collect the data of the photon nanojet along the propagation direction of the light beam. The result is shown in Figure 6(b). It can be seen that the lateral size of the photon nanojet satisfies the Gaussian distribution and is relatively small. The longitudinal size along the propagation direction of the light beam satisfies the Lorentz distribution and meets the characteristics of the photon nanojet.

[0028] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A transmission-type photon nanojet generator based on a suspended core optical fiber, characterized in that: The invention comprises a monochromatic light source, a single-mode optical fiber (1), a suspended core optical fiber (2), a high-resolution CCD (3) and a three-dimensional high-precision displacement stage; an air hole (4) with a diameter of 70-90 microns is provided inside the cladding (5) of the suspended core optical fiber (2), and a fiber core (6) is suspended on the inner wall of the air hole (4); the single-mode optical fiber (1) and the suspended core optical fiber (2) are placed vertically; the three-dimensional high-precision displacement stage controls the single-mode optical fiber (1) so that the light output from the core of the single-mode optical fiber (1) passes through the cladding (5) of the suspended core optical fiber (2) and can directly illuminate the optical fiber (6). The light emitted by the light source is incident vertically from the side of the hanging core optical fiber (2) to which the core (6) is attached after being outputted by the single-mode optical fiber (1), generating a transmission-type photon nanojet on the shadow surface of the core (6), and the photon nanojet is observed by a high-resolution CCD (3); the cladding (5) of the hanging core optical fiber (2) is processed with a microgroove on one side of the air hole (4), and the core (6) is exposed to the outside, so that the photon nanojet generated by the hanging core optical fiber (2) can be observed by the high-resolution CCD (3).

2. The transmission-type photonic nanojet generator based on suspended core optical fiber according to claim 1, characterized in that: The diameter of the suspended core optical fiber (2) is 125 microns, and the diameter of the fiber core (6) is 3-12 microns; the diameter of the single-mode optical fiber (1) is 125 microns, and the diameter of its fiber core is 8-10 microns.

3. The transmission-type photonic nanojet generator based on suspended core optical fiber according to claim 1, characterized in that: The photon nanojet generated by the core (6) of the suspended core optical fiber (2) is located in the air hole (4).

4. The transmission-type photonic nanojet generator based on suspended core optical fiber according to claim 1, characterized in that: The output end face of the single-mode optical fiber (1) is cut vertically and has a flat end face, so that the light beam is evenly irradiated onto the suspended core optical fiber (2).

5. The transmission-type photonic nanojet generator based on suspended core optical fiber according to claim 1, characterized in that: The modulation of the photon nano jet is achieved by thinning the core (6) of the suspended core optical fiber (2), filling the air hole (4) with media with different refractive indices, and changing parameters including light source.

6. The transmission-type photonic nanojet generator based on suspended core optical fiber according to claim 1, characterized in that: The wavelength range of the monochromatic light source is 400-1600nm.

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